A VOIP terminal digitizes an analog sound, and transmits the analog sound in a form of a data packet in real time over an IP data network. Three major domestic telecommunications operators are actively developing construction of an Ethernet Passive Optical Network (EPON)/Gigabit-Capable PON (GPON) in response to the national Broadband China strategy, thereby greatly increasing commercial application of VOIP services. A voice user terminal including a telephone, a fax machine or an integrated Point of Sale (POS) machine, and so on may be connected under a Plain Old Telephone Service (POTS) interface of the VOIP terminal. Generally, a ringing voltage parameter outputted by the VOIP terminal at present is set by a relevant technician according to experience, or is directly set as a default value. In the meanwhile, ringing voltage offset values are set as 0 in a unified manner. However, there is only one voice user terminal under one VOIP terminal in an existing network sometimes, while there are four or five voice user terminals sometimes. A telephone wire connecting the VOIP terminal and a voice user terminal may be long or short and different voice user terminals also require different voltages. Therefore, abnormal conditions that some voice user terminals ring briefly all the time, some voice user terminals are muted after ringing a sound, even some voice user terminals have no ringing all the time, and so on when the voice user terminals are connected to the same VOIP terminal are usually caused according to an existing ringing parameter setting manner.